Sex and Love do not equate. Over time, everything looses it 'luster' - what makes for a good relationship is a true understanding of each others needs and wants. This is tough job for both.
I have been married for over 50+ years, and yes, I have enjoyed the 'hobby' during that time - my job took me all over the US and I picked my 'playmates' very carefully (TER being one of the main factors I took into consideration when choosing one), I don't see anything wrong in this.
Anyone in the hobby (provider or client) will tell you its a business - guys have a hard time understanding that - its never 'love' (on their part) its 'lust'. Somehow guys think if you marry a provider you get 'freebies' - that is not the basis for a relationship.
You can be open and honest with your wife/girlfriend but there comes a point when you should just keep your mouth shut and go on with life.
There is no such thing as 'cheating' - we are human, seeing another for 'sex' is not a sin, and those who choose to work in this industry make that decision ever before they see their first client.
A good relationship is made up of caring for the other in good and bad times - as I stated before, everything looses it luster over time and if one wonders and finds another, chances are they are not relationship material to start with.
There is a lot of guys out there that have no idea what a provider deals with (mentally) - I have had a very long standing relationship with a provider and we both know each other boundaries.
All you can hope for is to find one who has the same likes and dislikes as you - leave sex out of it (since you both enjoy it), dig deeper and look for the real person